1. Field of the Invention
The present invention relates generally to a polarizing plate with optical compensation layers, a method of producing the same, and a liquid crystal panel, a liquid crystal display, and an image display, each of which includes the same.
2. Description of the Related Art
A semitransparent-reflective liquid crystal display has been proposed as a vertical alignment (VA) mode liquid crystal display in addition to a transmission liquid crystal display and a reflective liquid crystal display (see, for example, JP11(1999)-242226 A and JP 2001-209065 A). The semitransparent-reflective liquid crystal display allows displays to be visible by using outside light in bright places as in the reflective liquid crystal display and an internal light source such as a backlight in dark places. In other words, the semitransparent-reflective liquid crystal display employs a display system of combination of the reflective and transmission types. It switches the display mode into either a reflective mode or a transmission mode according to the brightness of the surrounding. Accordingly, the semitransparent-reflective liquid crystal display can provide a clear display even when the surrounding is dark, while reducing consumption power. Therefore, it is used suitably for display parts of mobile devices.
An example of such a semitransparent-reflective liquid crystal display is a liquid crystal display that includes an upper substrate, a lower substrate, a liquid crystal layer, and a reflective film that is allowed to function as a semitransparent-reflective plate. The liquid crystal layer is sandwiched between the upper substrate and the lower substrate. The reflective film is provided on the inner side of the lower substrate and is formed of a metal thin film such as aluminum that is provided with a window formed for light transmission. In this type of liquid crystal display, in the case of the reflective mode, outside light incident from the upper substrate side is transmitted through the liquid crystal layer, is then reflected by the reflective film disposed on the inner side of the lower substrate, is transmitted through the liquid crystal layer again, and is then emitted from the upper substrate side to contribute to the display. On the other hand, in the case of the transmission mode, light emitted from a backlight that has entered from the lower substrate side passes through the window of the reflective film to pass through the liquid crystal layer and is then emitted from the upper substrate side to contribute to the display. Accordingly, in the region where the reflective film is formed, the region where the window is formed serves as a transmissive display region and the other region serves as a reflective display region. However, in these VA mode liquid crystal displays, especially liquid crystal displays of a reflection type, a semitransparent type, and a semitransparent-reflective type, there is a problem in that light leakage is caused in a black display which reduces the contrast. Accordingly, there is a demand for the solution conventionally.
On the other hand, the liquid crystal display requires a polarizing plate. An elliptically polarizing plate including a retardation film stacked on a polarizing plate as an optical compensation layer is used increasingly. The elliptically polarizing plate is also referred to as a “polarizing plate with optical compensation layers”. It is used for supplying polarized light to the liquid crystal display while providing wide viewing angle properties at the same time. The polarizing plate with optical compensation layers is required to have not only the wide viewing angle properties but also a function that allows circularly polarized light to be obtained over a wide range of light wavelengths and contrast to be improved by preventing the above-mentioned light leakage from occurring in a black display. Moreover, in order to improve the brightness and to reduce the weight and thickness of the liquid crystal display, it is also required to improve the brightness and to reduce the weight and thickness of the polarizing plate with optical compensation layers. In addition, the polarizing plate with optical compensation layers has a problem of “thermal irregularity”, that is, optical functions become uneven due to heat. This problem occurs because the thickness thereof is too thick.